A3COSMOS: the dust attenuation of star-forming galaxies at z=2.5−4.0 from the COSMOS-ALMA archive

Fudamoto, Yoshinobu, Oesch, P A, Magnelli, B, Schinnerer, E, Liu, D, Lang, P, Jimenez-Andrade, E F, Groves, B, Leslie, S and Sargent, M T (2019) A3COSMOS: the dust attenuation of star-forming galaxies at z=2.5−4.0 from the COSMOS-ALMA archive. Monthly Notices Of The Royal Astronomical Society. pp. 1-12. ISSN 0035-8711

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Abstract

We present an analysis of the dust attenuation of star forming galaxies at z=2.5−4.0 through the relationship between the UV spectral slope ( β ), stellar mass ( M∗ ) and the infrared excess (IRX =LIR/LUV ) based on far-infrared continuum observations from the Atacama Large Millimeter/sub-millimeter Array (ALMA). Our study exploits the full ALMA archive over the COSMOS field processed by the A 3 COSMOS team, which includes an unprecedented sample of ∼1500 galaxies at z∼3 as primary or secondary targets in ALMA band 6 or 7 observations with a median continuum sensitivity of 126 μJy/beam (1 σ ). The detection rate is highly mass dependent, decreasing drastically below log(M∗/M⊙)=10.5 . The detected galaxies show that the IRX- β relationship of massive ( logM∗/M⊙>10 ) main sequence galaxies at z=2.5−4.0 is consistent with that of local galaxies, while starbursts are generally offset by ∼0.5dex to larger IRX values. At the low mass end, we derive upper limits on the infrared luminosities through stacking of the ALMA data. The combined IRX- M∗ relation at log(M∗/M⊙)>9 exhibits a significantly steeper slope than reported in previous studies at similar redshifts, implying little dust obscuration at logM∗/M⊙<10 . However, our results are consistent with early measurements at z∼5.5 , indicating a potential redshift evolution between z∼2 and z∼6 . Deeper observations targeting low mass galaxies will be required to confirm this finding.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Subjects: Q Science > QB Astronomy
Depositing User: Mark Sargent
Date Deposited: 12 Nov 2019 09:01
Last Modified: 27 Nov 2019 12:00
URI: http://sro.sussex.ac.uk/id/eprint/87975

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